#if !FEATURE_PAL    
namespace System.Diagnostics {
    using System.Text;
    using System.Threading;
    using System.Runtime.InteropServices;
    using System.ComponentModel;
    using System.ComponentModel.Design;
    using System.Diagnostics;
    using System;
    using System.Collections;
    using System.IO;
    using Microsoft.Win32;        
    using Microsoft.Win32.SafeHandles;
    using System.Collections.Specialized;
    using System.Globalization;
    using System.Security;
    using System.Security.Permissions;
    using System.Security.Principal;
    using System.Runtime.Versioning;
    using System.Diagnostics.Contracts;

    /// <devdoc>
    ///     This class finds the main window of a process.  It needs to be
    ///     class because we need to store state while searching the set
    ///     of windows.
    /// </devdoc>
    /// <internalonly/>
    internal class MainWindowFinder {
        IntPtr bestHandle;
        int processId;

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public IntPtr FindMainWindow(int processId) {
            bestHandle = (IntPtr)0;
            this.processId = processId;
            
            NativeMethods.EnumThreadWindowsCallback callback = new NativeMethods.EnumThreadWindowsCallback(this.EnumWindowsCallback);
            NativeMethods.EnumWindows(callback, IntPtr.Zero);

            GC.KeepAlive(callback);
            return bestHandle;
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        bool IsMainWindow(IntPtr handle) {
            
            if (NativeMethods.GetWindow(new HandleRef(this, handle), NativeMethods.GW_OWNER) != (IntPtr)0 || !NativeMethods.IsWindowVisible(new HandleRef(this, handle)))
                return false;
            
            // Microsoft: should we use no window title to mean not a main window? (task man does)
            
            /*
            int length = NativeMethods.GetWindowTextLength(handle) * 2;
            StringBuilder builder = new StringBuilder(length);
            if (NativeMethods.GetWindowText(handle, builder, builder.Capacity) == 0)
                return false;
            if (builder.ToString() == string.Empty)
                return false;
            */

            return true;
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        bool EnumWindowsCallback(IntPtr handle, IntPtr extraParameter) {
            int processId;
            NativeMethods.GetWindowThreadProcessId(new HandleRef(this, handle), out processId);
            if (processId == this.processId) {
                if (IsMainWindow(handle)) {
                    bestHandle = handle;
                    return false;
                }
            }
            return true;
        }
    }

    /// <devdoc>
    ///     This static class is a platform independent Api for querying information
    ///     about processes, threads and modules.  It delegates to the platform
    ///     specific classes WinProcessManager for Win9x and NtProcessManager
    ///     for WinNt.
    /// </devdoc>
    /// <internalonly/>
    internal static class ProcessManager {
    
        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        static ProcessManager() {
            // In order to query information (OpenProcess) on some protected processes
            // like csrss, we need SeDebugPrivilege privilege.
            // After removing the depenecy on Performance Counter, we don't have a chance
            // to run the code in CLR performance counter to ask for this privilege.
            // So we will try to get the privilege here.
            // We could fail if the user account doesn't have right to do this, but that's fair.
            
            NativeMethods.LUID luid = new NativeMethods.LUID();
            if (!NativeMethods.LookupPrivilegeValue(null, "SeDebugPrivilege", out luid)) {
                return;
            }
            
            IntPtr tokenHandle = IntPtr.Zero;
            try {
                if( !NativeMethods.OpenProcessToken(
                        new HandleRef(null, NativeMethods.GetCurrentProcess()), 
                        (int)TokenAccessLevels.AdjustPrivileges, 
                        out tokenHandle)) {
                    return;
                }

                NativeMethods.TokenPrivileges tp = new NativeMethods.TokenPrivileges();
                tp.PrivilegeCount = 1;
                tp.Luid = luid;
                tp.Attributes = NativeMethods.SE_PRIVILEGE_ENABLED;

                // AdjustTokenPrivileges can return true even if it didn't succeed (when ERROR_NOT_ALL_ASSIGNED is returned).
                NativeMethods.AdjustTokenPrivileges(new HandleRef(null,tokenHandle), false, tp, 0, IntPtr.Zero, IntPtr.Zero);
            }
            finally {
                if( tokenHandle != IntPtr.Zero) {
                    SafeNativeMethods.CloseHandle(tokenHandle);
                }
            }
        }


    
        public static bool IsNt {
            get {
                return Environment.OSVersion.Platform == PlatformID.Win32NT;
            }
        }

       public static bool IsOSOlderThanXP  {
            get {
                return Environment.OSVersion.Version.Major < 5 ||
                            (Environment.OSVersion.Version.Major == 5 && Environment.OSVersion.Version.Minor == 0);
            }
       }

        /// <summary>Gets the ProcessInfo for the specified process ID on the specified machine.</summary>
        /// <param name="processId">The process ID.</param>
        /// <param name="machineName">The machine name.</param>
        /// <returns>The ProcessInfo for the process if it could be found; otherwise, null.</returns>
        public static ProcessInfo GetProcessInfo(int processId, string machineName) {
            bool isRemoteMachine = IsRemoteMachine(machineName);

            if (!isRemoteMachine && IsNt && (Environment.OSVersion.Version.Major >= 5)) {
                ProcessInfo[] processInfos = NtProcessInfoHelper.GetProcessInfos(pid => pid == processId);
                if (processInfos.Length == 1) {
                	return processInfos[0];
                }
            }
            else {
                ProcessInfo[] processInfos = ProcessManager.GetProcessInfosCore(machineName, isRemoteMachine);
                foreach (ProcessInfo processInfo in processInfos) {
                    if (processInfo.processId == processId) {
                        return processInfo;
                    }
                }
            }

            return null;
        }

        public static ProcessInfo[] GetProcessInfos(string machineName) {
            bool isRemoteMachine = IsRemoteMachine(machineName);
            return GetProcessInfosCore(machineName, isRemoteMachine);
        }

        private static ProcessInfo[] GetProcessInfosCore(string machineName, bool isRemoteMachine) {
            if (IsNt) {
                // Do not use performance counter for local machine with Win2000 and above
                if( !isRemoteMachine && 
                    (Environment.OSVersion.Version.Major >= 5 ))   {
                    return NtProcessInfoHelper.GetProcessInfos();
                }
                return NtProcessManager.GetProcessInfos(machineName, isRemoteMachine);
            }

            else {
                if (isRemoteMachine)
                    throw new PlatformNotSupportedException(SR.GetString(SR.WinNTRequiredForRemote));
                return WinProcessManager.GetProcessInfos();
            }
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int[] GetProcessIds() {
            if (IsNt)
                return NtProcessManager.GetProcessIds();
            else {
                return WinProcessManager.GetProcessIds();
            }
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int[] GetProcessIds(string machineName) {
            if (IsRemoteMachine(machineName)) {
                if (IsNt) {
                    return NtProcessManager.GetProcessIds(machineName, true);
                }
                else {
                    throw new PlatformNotSupportedException(SR.GetString(SR.WinNTRequiredForRemote));
                }
            }
            else {
                return GetProcessIds();
            }
        }

        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
        public static bool IsProcessRunning(int processId, string machineName) {
            return IsProcessRunning(processId, GetProcessIds(machineName));
        }

        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
        public static bool IsProcessRunning(int processId) {
            return IsProcessRunning(processId, GetProcessIds());
        }

        static bool IsProcessRunning(int processId, int[] processIds) {
            for (int i = 0; i < processIds.Length; i++)
                if (processIds[i] == processId)
                    return true;
            return false;
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int GetProcessIdFromHandle(SafeProcessHandle processHandle) {
            if (IsNt)
                return NtProcessManager.GetProcessIdFromHandle(processHandle);
            else
                throw new PlatformNotSupportedException(SR.GetString(SR.WinNTRequired));
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static IntPtr GetMainWindowHandle(int processId) {
            MainWindowFinder finder = new MainWindowFinder();
            return finder.FindMainWindow(processId);
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public static ModuleInfo[] GetModuleInfos(int processId) {
            if (IsNt)
                return NtProcessManager.GetModuleInfos(processId);
            else
                return WinProcessManager.GetModuleInfos(processId);
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static SafeProcessHandle OpenProcess(int processId, int access, bool throwIfExited) {
            SafeProcessHandle processHandle = NativeMethods.OpenProcess(access, false, processId);
            int result = Marshal.GetLastWin32Error();            
            if (!processHandle.IsInvalid) {
                return processHandle;
            }

            if (processId == 0) { 
                throw new Win32Exception(5);
            }

            // If the handle is invalid because the process has exited, only throw an exception if throwIfExited is true.            
            if (!IsProcessRunning(processId)) {
                if (throwIfExited) {
                    throw new InvalidOperationException(SR.GetString(SR.ProcessHasExited, processId.ToString(CultureInfo.CurrentCulture)));
                }
                else {
                    return SafeProcessHandle.InvalidHandle;
                }
            }
            throw new Win32Exception(result);            
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public static SafeThreadHandle OpenThread(int threadId, int access) {
            try {
                SafeThreadHandle threadHandle = NativeMethods.OpenThread(access, false, threadId);
                int result = Marshal.GetLastWin32Error();                
                if (threadHandle.IsInvalid) {
                    if (result == NativeMethods.ERROR_INVALID_PARAMETER)
                        throw new InvalidOperationException(SR.GetString(SR.ThreadExited, threadId.ToString(CultureInfo.CurrentCulture)));
                    throw new Win32Exception(result);
                }
                return threadHandle;
            }
            catch (EntryPointNotFoundException x) {
                throw new PlatformNotSupportedException(SR.GetString(SR.Win2000Required), x);
            }
        }



        public static bool IsRemoteMachine(string machineName) {
            if (machineName == null)
                throw new ArgumentNullException("machineName");
            
            if (machineName.Length == 0)
                throw new ArgumentException(SR.GetString(SR.InvalidParameter, "machineName", machineName));
                        
            string baseName;

            if (machineName.StartsWith("\\", StringComparison.Ordinal)) 
                baseName = machineName.Substring(2);
            else
                baseName = machineName;
            if (baseName.Equals(".")) return false;

            StringBuilder sb = new StringBuilder(256);
            SafeNativeMethods.GetComputerName(sb, new int[] {sb.Capacity});
            string computerName = sb.ToString();
            if (String.Compare(computerName, baseName, StringComparison.OrdinalIgnoreCase) == 0) return false;
            return true;
        }
    }

    /// <devdoc>
    ///     This static class provides the process api for the Win9x platform.
    ///     We use the toolhelp32 api to query process, thread and module information.
    /// </devdoc>
    /// <internalonly/>
    internal static class WinProcessManager {

        // This is expensive.  We should specialize getprocessinfos and only get 
        // the ids instead of getting all the info and then copying the ids out.
        public static int[] GetProcessIds() {
            ProcessInfo[] infos = GetProcessInfos();
            int[] ids = new int[infos.Length];
            for (int i = 0; i < infos.Length; i++) {
                ids[i] = infos[i].processId;
            }
            return ids;
        }

        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
        public static ProcessInfo[] GetProcessInfos() {
            IntPtr handle = (IntPtr)(-1);
            GCHandle bufferHandle = new GCHandle();
            ArrayList threadInfos = new ArrayList();
            Hashtable processInfos = new Hashtable();

            try {
                handle = NativeMethods.CreateToolhelp32Snapshot(NativeMethods.TH32CS_SNAPPROCESS | NativeMethods.TH32CS_SNAPTHREAD, 0);
                if (handle == (IntPtr)(-1)) throw new Win32Exception();
                int entrySize = (int)Marshal.SizeOf(typeof(NativeMethods.WinProcessEntry));
                int bufferSize = entrySize + NativeMethods.WinProcessEntry.sizeofFileName;
                int[] buffer = new int[bufferSize / 4];
                bufferHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
                IntPtr bufferPtr = bufferHandle.AddrOfPinnedObject();
                Marshal.WriteInt32(bufferPtr, bufferSize);

                HandleRef handleRef = new HandleRef(null, handle);
                
                if (NativeMethods.Process32First(handleRef, bufferPtr)) {
                    do {
                        NativeMethods.WinProcessEntry process = new NativeMethods.WinProcessEntry();
                        Marshal.PtrToStructure(bufferPtr, process);
                        ProcessInfo processInfo = new ProcessInfo();
                        String name = Marshal.PtrToStringAnsi((IntPtr)((long)bufferPtr + entrySize));  
                        processInfo.processName = Path.ChangeExtension(Path.GetFileName(name), null);
                        processInfo.handleCount = process.cntUsage;
                        processInfo.processId = process.th32ProcessID;
                        processInfo.basePriority = process.pcPriClassBase;
                        processInfo.mainModuleId = process.th32ModuleID;
                        processInfos.Add(processInfo.processId, processInfo);
                        Marshal.WriteInt32(bufferPtr, bufferSize);
                    }
                    while (NativeMethods.Process32Next(handleRef, bufferPtr));
                }
                
                NativeMethods.WinThreadEntry thread = new NativeMethods.WinThreadEntry();
                thread.dwSize = Marshal.SizeOf(thread);
                if (NativeMethods.Thread32First(handleRef, thread)) {
                    do {
                        ThreadInfo threadInfo = new ThreadInfo();
                        threadInfo.threadId = thread.th32ThreadID;
                        threadInfo.processId = thread.th32OwnerProcessID;
                        threadInfo.basePriority = thread.tpBasePri;
                        threadInfo.currentPriority = thread.tpBasePri + thread.tpDeltaPri;
                        threadInfos.Add(threadInfo);
                    }
                    while (NativeMethods.Thread32Next(handleRef, thread));
                }

                for (int i = 0; i < threadInfos.Count; i++) {
                    ThreadInfo threadInfo = (ThreadInfo)threadInfos[i];
                    ProcessInfo processInfo = (ProcessInfo)processInfos[threadInfo.processId];
                    if (processInfo != null) 
                        processInfo.threadInfoList.Add(threadInfo);
                    //else 
                    //    throw new InvalidOperationException(SR.GetString(SR.ProcessNotFound, threadInfo.threadId.ToString(), threadInfo.processId.ToString()));                   
                }
            }
            finally {
                if (bufferHandle.IsAllocated) bufferHandle.Free();
                Debug.WriteLineIf(Process.processTracing.TraceVerbose, "Process - CloseHandle(toolhelp32 snapshot handle)");
                if (handle != (IntPtr)(-1)) SafeNativeMethods.CloseHandle(handle);
            }

            ProcessInfo[] temp = new ProcessInfo[processInfos.Values.Count];
            processInfos.Values.CopyTo(temp, 0);
            return temp;
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public static ModuleInfo[] GetModuleInfos(int processId) {
            IntPtr handle = (IntPtr)(-1);
            GCHandle bufferHandle = new GCHandle();
            ArrayList moduleInfos = new ArrayList();

            try {
                handle = NativeMethods.CreateToolhelp32Snapshot(NativeMethods.TH32CS_SNAPMODULE, processId);
                if (handle == (IntPtr)(-1)) throw new Win32Exception();
                int entrySize = Marshal.SizeOf(typeof(NativeMethods.WinModuleEntry));
                int bufferSize = entrySize + NativeMethods.WinModuleEntry.sizeofFileName + NativeMethods.WinModuleEntry.sizeofModuleName;
                int[] buffer = new int[bufferSize / 4];
                bufferHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
                IntPtr bufferPtr = bufferHandle.AddrOfPinnedObject();
                Marshal.WriteInt32(bufferPtr, bufferSize);

                HandleRef handleRef = new HandleRef(null, handle);

                if (NativeMethods.Module32First(handleRef, bufferPtr)) {
                    do {
                        NativeMethods.WinModuleEntry module = new NativeMethods.WinModuleEntry();
                        Marshal.PtrToStructure(bufferPtr, module);
                        ModuleInfo moduleInfo = new ModuleInfo();
                        moduleInfo.baseName = Marshal.PtrToStringAnsi((IntPtr)((long)bufferPtr + entrySize));
                        moduleInfo.fileName = Marshal.PtrToStringAnsi((IntPtr)((long)bufferPtr + entrySize + NativeMethods.WinModuleEntry.sizeofModuleName));
                        moduleInfo.baseOfDll = module.modBaseAddr;
                        moduleInfo.sizeOfImage = module.modBaseSize;
                        moduleInfo.Id = module.th32ModuleID;
                        moduleInfos.Add(moduleInfo);
                        Marshal.WriteInt32(bufferPtr, bufferSize);
                    }
                    while (NativeMethods.Module32Next(handleRef, bufferPtr));
                }
            }
            finally {
                if (bufferHandle.IsAllocated) bufferHandle.Free();
                Debug.WriteLineIf(Process.processTracing.TraceVerbose, "Process - CloseHandle(toolhelp32 snapshot handle)");
                if (handle != (IntPtr)(-1)) SafeNativeMethods.CloseHandle(handle);
            }

            ModuleInfo[] temp = new ModuleInfo[moduleInfos.Count];
            moduleInfos.CopyTo(temp, 0);
            return temp;
        }

    }


    /// <devdoc>
    ///     This static class provides the process api for the WinNt platform.
    ///     We use the performance counter api to query process and thread
    ///     information.  Module information is obtained using PSAPI.
    /// </devdoc>
    /// <internalonly/>
    internal static class NtProcessManager {
        private const int ProcessPerfCounterId = 230;
        private const int ThreadPerfCounterId = 232;
        private const string PerfCounterQueryString = "230 232";
        internal const int IdleProcessID = 0;
        
        static Hashtable valueIds;

        static NtProcessManager() {
            valueIds = new Hashtable();
            valueIds.Add("Handle Count", ValueId.HandleCount);
            valueIds.Add("Pool Paged Bytes", ValueId.PoolPagedBytes);
            valueIds.Add("Pool Nonpaged Bytes", ValueId.PoolNonpagedBytes);
            valueIds.Add("Elapsed Time", ValueId.ElapsedTime);
            valueIds.Add("Virtual Bytes Peak", ValueId.VirtualBytesPeak);
            valueIds.Add("Virtual Bytes", ValueId.VirtualBytes);
            valueIds.Add("Private Bytes", ValueId.PrivateBytes);
            valueIds.Add("Page File Bytes", ValueId.PageFileBytes);
            valueIds.Add("Page File Bytes Peak", ValueId.PageFileBytesPeak);
            valueIds.Add("Working Set Peak", ValueId.WorkingSetPeak);
            valueIds.Add("Working Set", ValueId.WorkingSet);
            valueIds.Add("ID Thread", ValueId.ThreadId);
            valueIds.Add("ID Process", ValueId.ProcessId);
            valueIds.Add("Priority Base", ValueId.BasePriority);
            valueIds.Add("Priority Current", ValueId.CurrentPriority);
            valueIds.Add("% User Time", ValueId.UserTime);
            valueIds.Add("% Privileged Time", ValueId.PrivilegedTime);
            valueIds.Add("Start Address", ValueId.StartAddress);
            valueIds.Add("Thread State", ValueId.ThreadState);
            valueIds.Add("Thread Wait Reason", ValueId.ThreadWaitReason);
        }

        internal static int SystemProcessID {
            get {
                const int systemProcessIDOnXP = 4;
                const int systemProcessIDOn2K = 8;
                
                if( ProcessManager.IsOSOlderThanXP) {
                    return systemProcessIDOn2K;
                }
                else {
                    return systemProcessIDOnXP;
                }
            }
        }
      
        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int[] GetProcessIds(string machineName, bool isRemoteMachine) {            
            ProcessInfo[] infos = GetProcessInfos(machineName, isRemoteMachine);
            int[] ids = new int[infos.Length];
            for (int i = 0; i < infos.Length; i++)
                ids[i] = infos[i].processId;
            return ids;
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int[] GetProcessIds() {
            int[] processIds = new int[256];
            int size;
            for (;;) {
                if (!NativeMethods.EnumProcesses(processIds, processIds.Length * 4, out size))
                    throw new Win32Exception();
                if (size == processIds.Length * 4) {
                    processIds = new int[processIds.Length * 2];
                    continue;
                }
                break;
            }
            int[] ids = new int[size / 4];
            Array.Copy(processIds, ids, ids.Length);
            return ids;
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public static ModuleInfo[] GetModuleInfos(int processId) {
            return GetModuleInfos(processId, false);
        }

        [ResourceExposure(ResourceScope.Process)]
        [ResourceConsumption(ResourceScope.Process)]
        public static ModuleInfo GetFirstModuleInfo(int processId) {
            ModuleInfo[] moduleInfos = GetModuleInfos(processId, true);
            if( moduleInfos.Length == 0) {
                return null;
            }
            else {
                return moduleInfos[0];
            }        
        }        
        
        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
        private static ModuleInfo[] GetModuleInfos(int processId, bool firstModuleOnly) {
            Contract.Ensures(Contract.Result<ModuleInfo[]>().Length >= 1);

            // preserving Everett behavior.    
            if( processId == SystemProcessID || processId == IdleProcessID) { 
                // system process and idle process doesn't have any modules 
                throw new Win32Exception(HResults.EFail,SR.GetString(SR.EnumProcessModuleFailed));
            }
            
            SafeProcessHandle processHandle = SafeProcessHandle.InvalidHandle;            
            try {
                processHandle = ProcessManager.OpenProcess(processId, NativeMethods.PROCESS_QUERY_INFORMATION | NativeMethods.PROCESS_VM_READ, true);

                IntPtr[] moduleHandles = new IntPtr[64];
                GCHandle moduleHandlesArrayHandle = new GCHandle();
                int moduleCount = 0;
                for (;;) {
                    bool enumResult = false;
                    try {
                        moduleHandlesArrayHandle = GCHandle.Alloc(moduleHandles, GCHandleType.Pinned);                        
                        enumResult = NativeMethods.EnumProcessModules(processHandle, moduleHandlesArrayHandle.AddrOfPinnedObject(), moduleHandles.Length * IntPtr.Size, ref moduleCount);

                        // The API we need to use to enumerate process modules differs on two factors:
                        //   1) If our process is running in WOW64.
                        //   2) The bitness of the process we wish to introspect.
                        //
                        // If we are not running in WOW64 or we ARE in WOW64 but want to inspect a 32 bit process
                        // we can call psapi!EnumProcessModules.
                        //  
                        // If we are running in WOW64 and we want to inspect the modules of a 64 bit process then
                        // psapi!EnumProcessModules will return false with ERROR_PARTIAL_COPY (299).  In this case we can't 
                        // do the enumeration at all.  So we'll detect this case and bail out.
                        //
                        // Also, EnumProcessModules is not a reliable method to get the modules for a process. 
                        // If OS loader is touching module information, this method might fail and copy part of the data.
                        // This is no easy solution to this problem. The only reliable way to fix this is to 
                        // suspend all the threads in target process. Of course we don't want to do this in Process class.
                        // So we just to try avoid the ---- by calling the same method 50 (an arbitary number) times.
                        //
                        if (!enumResult) {
                            bool sourceProcessIsWow64 = false;
                            bool targetProcessIsWow64 = false;
                            if (!ProcessManager.IsOSOlderThanXP) {
                                SafeProcessHandle hCurProcess = SafeProcessHandle.InvalidHandle;
                                try {
                                    hCurProcess = ProcessManager.OpenProcess(NativeMethods.GetCurrentProcessId(), NativeMethods.PROCESS_QUERY_INFORMATION, true);
                                    bool wow64Ret;

                                    wow64Ret = SafeNativeMethods.IsWow64Process(hCurProcess, ref sourceProcessIsWow64);
                                    if (!wow64Ret) {
                                        throw new Win32Exception();
                                    }

                                    wow64Ret = SafeNativeMethods.IsWow64Process(processHandle, ref targetProcessIsWow64);
                                    if (!wow64Ret) {
                                        throw new Win32Exception();
                                    }

                                    if (sourceProcessIsWow64 && !targetProcessIsWow64) {
                                        // Wow64 isn't going to allow this to happen, the best we can do is give a descriptive error to the user.
                                        throw new Win32Exception(NativeMethods.ERROR_PARTIAL_COPY, SR.GetString(SR.EnumProcessModuleFailedDueToWow));
                                    }

                                } finally {
                                    if (hCurProcess != SafeProcessHandle.InvalidHandle) {
                                        hCurProcess.Close();
                                    }
                                }
                            }

                            // If the failure wasn't due to Wow64, try again.
                            for (int i = 0; i < 50; i++) {
                                enumResult = NativeMethods.EnumProcessModules(processHandle, moduleHandlesArrayHandle.AddrOfPinnedObject(), moduleHandles.Length * IntPtr.Size, ref moduleCount);
                                if (enumResult) {
                                    break;
                                }
                                Thread.Sleep(1);
                            }
                        }
                    }
                    finally {
                        moduleHandlesArrayHandle.Free();
                    }       
                    
                    if (!enumResult) {
                        throw new Win32Exception();
                    }
                    
                    moduleCount /= IntPtr.Size;
                    if (moduleCount <= moduleHandles.Length) break;
                    moduleHandles = new IntPtr[moduleHandles.Length * 2];
                }
                ArrayList moduleInfos = new ArrayList();
                
                int ret;
                for (int i = 0; i < moduleCount; i++) {
                    try
                    {
                        ModuleInfo moduleInfo = new ModuleInfo();
                        IntPtr moduleHandle = moduleHandles[i];
                        NativeMethods.NtModuleInfo ntModuleInfo = new NativeMethods.NtModuleInfo();
                        if (!NativeMethods.GetModuleInformation(processHandle, new HandleRef(null, moduleHandle), ntModuleInfo, Marshal.SizeOf(ntModuleInfo)))
                            throw new Win32Exception();
                        moduleInfo.sizeOfImage = ntModuleInfo.SizeOfImage;
                        moduleInfo.entryPoint = ntModuleInfo.EntryPoint;
                        moduleInfo.baseOfDll = ntModuleInfo.BaseOfDll;

                        StringBuilder baseName = new StringBuilder(1024);
                        ret = NativeMethods.GetModuleBaseName(processHandle, new HandleRef(null, moduleHandle), baseName, baseName.Capacity * 2);
                        if (ret == 0) throw new Win32Exception();
                        moduleInfo.baseName = baseName.ToString();

                        StringBuilder fileName = new StringBuilder(1024);
                        ret = NativeMethods.GetModuleFileNameEx(processHandle, new HandleRef(null, moduleHandle), fileName, fileName.Capacity * 2);
                        if (ret == 0) throw new Win32Exception();
                        moduleInfo.fileName = fileName.ToString();

                        // smss.exe is started before the win32 subsystem so it get this funny "\systemroot\.." path.
                        // We change this to the actual path by appending "smss.exe" to GetSystemDirectory()
                        if (string.Compare(moduleInfo.fileName, "\\SystemRoot\\System32\\smss.exe", StringComparison.OrdinalIgnoreCase) == 0) {
                            moduleInfo.fileName = Path.Combine(Environment.SystemDirectory, "smss.exe");
                        }
                        // Avoid returning Unicode-style long string paths.  IO methods cannot handle them.
                        if (moduleInfo.fileName != null
                            && moduleInfo.fileName.Length >= 4
                            && moduleInfo.fileName.StartsWith(@"\\?\", StringComparison.Ordinal)) {

                            moduleInfo.fileName = moduleInfo.fileName.Substring(4);
                        }

                        moduleInfos.Add(moduleInfo);
                    }
                    catch (Win32Exception e)
                    {
                        if (e.NativeErrorCode == NativeMethods.ERROR_INVALID_HANDLE || e.NativeErrorCode == NativeMethods.ERROR_PARTIAL_COPY)
                        {
                            // It's possible that another thread casued this module to become
                            // unloaded (e.g FreeLibrary was called on the module).  Ignore it and
                            // move on.
                        }                           
                        else
                        {
                            throw;
                        }
                    }

                    //
                    // If the user is only interested in the main module, break now.
                    // This avoid some waste of time. In addition, if the application unloads a DLL                     
                    // we will not get an exception. 
                    //
                    if( firstModuleOnly) { break; }     
                }
                ModuleInfo[] temp = new ModuleInfo[moduleInfos.Count];
                moduleInfos.CopyTo(temp, 0);
                return temp;
            }
            finally {
                Debug.WriteLineIf(Process.processTracing.TraceVerbose, "Process - CloseHandle(process)");
                if (!processHandle.IsInvalid ) { 
                    processHandle.Close();
                }
            }
        }

        [ResourceExposure(ResourceScope.Machine)]
        [ResourceConsumption(ResourceScope.Machine)]
        public static int GetProcessIdFromHandle(SafeProcessHandle processHandle) {
            NativeMethods.NtProcessBasicInfo info = new NativeMethods.NtProcessBasicInfo();
            int status = NativeMethods.NtQueryInformationProcess(processHandle, NativeMethods.NtQueryProcessBasicInfo, info, (int)Marshal.SizeOf(info), null);
            if (status != 0) {
                throw new InvalidOperationException(SR.GetString(SR.CantGetProcessId), new Win32Exception(status));
            }
            // We should change the signature of this function and ID property in process class.
            return info.UniqueProcessId.ToInt32();
        }

        public static ProcessInfo[] GetProcessInfos(string machineName, bool isRemoteMachine) {
            // We demand unmanaged code here because PerformanceCounterLib doesn't demand
            // anything.  This is the only place we do GetPerformanceCounterLib, and it isn't cached.
            new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Demand();
            PerformanceCounterLib library = null;
            try {
                library = PerformanceCounterLib.GetPerformanceCounterLib(machineName, new CultureInfo(0x009));                            
                return GetProcessInfos(library);
            }
            catch(Exception e) {
                if( isRemoteMachine) {
                    throw new InvalidOperationException(SR.GetString(SR.CouldntConnectToRemoteMachine), e);
                }
                else {
                    throw e;
                }
            }
            // We don't want to call library.Close() here because that would cause us to unload all of the perflibs.
            // On the next call to GetProcessInfos, we'd have to load them all up again, which is SLOW!
        }

        static ProcessInfo[] GetProcessInfos(PerformanceCounterLib library) {
            ProcessInfo[] processInfos = new ProcessInfo[0] ;
            byte[] dataPtr = null;
            
            int retryCount = 5;
            while (processInfos.Length == 0 && retryCount != 0) {                    
                try {
                    dataPtr = library.GetPerformanceData(PerfCounterQueryString);
                    processInfos = GetProcessInfos(library, ProcessPerfCounterId, ThreadPerfCounterId, dataPtr);
                }
                catch (Exception e) {
                    throw new InvalidOperationException(SR.GetString(SR.CouldntGetProcessInfos), e);
                }
                                        
                --retryCount;                        
            }                    
        
            if (processInfos.Length == 0)
                throw new InvalidOperationException(SR.GetString(SR.ProcessDisabled));    
                
            return processInfos;                    
                        
        }

        static ProcessInfo[] GetProcessInfos(PerformanceCounterLib library, int processIndex, int threadIndex, byte[] data) {
            Debug.WriteLineIf(Process.processTracing.TraceVerbose, "GetProcessInfos()");
            Hashtable processInfos = new Hashtable();
            ArrayList threadInfos = new ArrayList();

            GCHandle dataHandle = new GCHandle();             
            try {
                dataHandle = GCHandle.Alloc(data, GCHandleType.Pinned);
                IntPtr dataBlockPtr = dataHandle.AddrOfPinnedObject();
                NativeMethods.PERF_DATA_BLOCK dataBlock = new NativeMethods.PERF_DATA_BLOCK();
                Marshal.PtrToStructure(dataBlockPtr, dataBlock);
                IntPtr typePtr = (IntPtr)((long)dataBlockPtr + dataBlock.HeaderLength);
                NativeMethods.PERF_INSTANCE_DEFINITION instance = new NativeMethods.PERF_INSTANCE_DEFINITION();
                NativeMethods.PERF_COUNTER_BLOCK counterBlock = new NativeMethods.PERF_COUNTER_BLOCK();                        
                for (int i = 0; i < dataBlock.NumObjectTypes; i++) {
                    NativeMethods.PERF_OBJECT_TYPE type = new NativeMethods.PERF_OBJECT_TYPE();
                    Marshal.PtrToStructure(typePtr, type);
                    IntPtr instancePtr = (IntPtr)((long)typePtr + type.DefinitionLength);
                    IntPtr counterPtr = (IntPtr)((long)typePtr + type.HeaderLength);
                    ArrayList counterList = new ArrayList();
                    
                    for (int j = 0; j < type.NumCounters; j++) {                    
                        NativeMethods.PERF_COUNTER_DEFINITION counter = new NativeMethods.PERF_COUNTER_DEFINITION();
                        Marshal.PtrToStructure(counterPtr, counter);
                        string counterName = library.GetCounterName(counter.CounterNameTitleIndex);

                        if (type.ObjectNameTitleIndex == processIndex)
                            counter.CounterNameTitlePtr = (int)GetValueId(counterName);
                        else if (type.ObjectNameTitleIndex == threadIndex)
                            counter.CounterNameTitlePtr = (int)GetValueId(counterName);
                        counterList.Add(counter);
                        counterPtr = (IntPtr)((long)counterPtr + counter.ByteLength);
                    }
                    NativeMethods.PERF_COUNTER_DEFINITION[] counters = new NativeMethods.PERF_COUNTER_DEFINITION[counterList.Count];
                    counterList.CopyTo(counters, 0);
                    for (int j = 0; j < type.NumInstances; j++) {
                        Marshal.PtrToStructure(instancePtr, instance);
                        IntPtr namePtr = (IntPtr)((long)instancePtr + instance.NameOffset);
                        string instanceName = Marshal.PtrToStringUni(namePtr);            
                        if (instanceName.Equals("_Total")) continue;
                        IntPtr counterBlockPtr = (IntPtr)((long)instancePtr + instance.ByteLength);
                        Marshal.PtrToStructure(counterBlockPtr, counterBlock);
                        if (type.ObjectNameTitleIndex == processIndex) {
                            ProcessInfo processInfo = GetProcessInfo(type, (IntPtr)((long)instancePtr + instance.ByteLength), counters);
                            if (processInfo.processId == 0 && string.Compare(instanceName, "Idle", StringComparison.OrdinalIgnoreCase) != 0) {
                                // Sometimes we'll get a process structure that is not completely filled in.
                                // We can catch some of these by looking for non-"idle" processes that have id 0
                                // and ignoring those.
                                Debug.WriteLineIf(Process.processTracing.TraceVerbose, "GetProcessInfos() - found a non-idle process with id 0; ignoring.");
                            }
                            else {
                                if (processInfos[processInfo.processId] != null) {
                                    // We've found two entries in the perfcounters that claim to be the
                                    // same process.  We throw an exception.  Is this really going to be
                                    // helpfull to the user?  Should we just ignore?
                                    Debug.WriteLineIf(Process.processTracing.TraceVerbose, "GetProcessInfos() - found a duplicate process id");
                                }
                                else {
                                    // the performance counters keep a 15 character prefix of the exe name, and then delete the ".exe",
                                    // if it's in the first 15.  The problem is that sometimes that will leave us with part of ".exe"
                                    // at the end.  If instanceName ends in ".", ".e", or ".ex" we remove it.
                                    string processName = instanceName;
                                    if (processName.Length == 15) {
                                        if      (instanceName.EndsWith(".", StringComparison.Ordinal  )) processName = instanceName.Substring(0, 14);
                                        else if (instanceName.EndsWith(".e", StringComparison.Ordinal )) processName = instanceName.Substring(0, 13);
                                        else if (instanceName.EndsWith(".ex", StringComparison.Ordinal)) processName = instanceName.Substring(0, 12);
                                    }
                                    processInfo.processName = processName;
                                    processInfos.Add(processInfo.processId, processInfo);
                                }
                            }
                        }
                        else if (type.ObjectNameTitleIndex == threadIndex) {
                            ThreadInfo threadInfo = GetThreadInfo(type, (IntPtr)((long)instancePtr + instance.ByteLength), counters);
                            if (threadInfo.threadId != 0) threadInfos.Add(threadInfo);
                        }
                        instancePtr = (IntPtr)((long)instancePtr + instance.ByteLength + counterBlock.ByteLength);
                    }                                
                    
                    typePtr = (IntPtr)((long)typePtr + type.TotalByteLength);
                }
            }
            finally {
                if (dataHandle.IsAllocated) dataHandle.Free();
            }

            for (int i = 0; i < threadInfos.Count; i++) {
                ThreadInfo threadInfo = (ThreadInfo)threadInfos[i];
                ProcessInfo processInfo = (ProcessInfo)processInfos[threadInfo.processId];
                if (processInfo != null) {
                    processInfo.threadInfoList.Add(threadInfo);
                }
            }
                        
            ProcessInfo[] temp = new ProcessInfo[processInfos.Values.Count];
            processInfos.Values.CopyTo(temp, 0);
            return temp;
        }

        static ThreadInfo GetThreadInfo(NativeMethods.PERF_OBJECT_TYPE type, IntPtr instancePtr, NativeMethods.PERF_COUNTER_DEFINITION[] counters) {
            ThreadInfo threadInfo = new ThreadInfo();
            for (int i = 0; i < counters.Length; i++) {
                NativeMethods.PERF_COUNTER_DEFINITION counter = counters[i];
                long value = ReadCounterValue(counter.CounterType, (IntPtr)((long)instancePtr + counter.CounterOffset));
                switch ((ValueId)counter.CounterNameTitlePtr) {
                    case ValueId.ProcessId:
                        threadInfo.processId = (int)value;
                        break;
                    case ValueId.ThreadId:
                        threadInfo.threadId = (int)value;
                        break;
                    case ValueId.BasePriority:
                        threadInfo.basePriority = (int)value;
                        break;
                    case ValueId.CurrentPriority:
                        threadInfo.currentPriority = (int)value;
                        break;
                    case ValueId.StartAddress:
                        threadInfo.startAddress = (IntPtr)value;
                        break;
                    case ValueId.ThreadState:
                        threadInfo.threadState = (ThreadState)value;
                        break;
                    case ValueId.ThreadWaitReason:
                        threadInfo.threadWaitReason = GetThreadWaitReason((int)value);
                        break;
                }
            }

            return threadInfo;
        }

        internal static ThreadWaitReason GetThreadWaitReason(int value) {
            switch (value) {
                case 0:
                case 7: return ThreadWaitReason.Executive;
                case 1:
                case 8: return ThreadWaitReason.FreePage;
                case 2:
                case 9: return ThreadWaitReason.PageIn;
                case 3:
                case 10: return ThreadWaitReason.SystemAllocation;
                case 4:
                case 11: return ThreadWaitReason.ExecutionDelay;
                case 5:
                case 12: return ThreadWaitReason.Suspended;
                case 6:
                case 13: return ThreadWaitReason.UserRequest;
                case 14: return ThreadWaitReason.EventPairHigh;;
                case 15: return ThreadWaitReason.EventPairLow;
                case 16: return ThreadWaitReason.LpcReceive;
                case 17: return ThreadWaitReason.LpcReply;
                case 18: return ThreadWaitReason.VirtualMemory;
                case 19: return ThreadWaitReason.PageOut;
                default: return ThreadWaitReason.Unknown;
            }
        }

        static ProcessInfo GetProcessInfo(NativeMethods.PERF_OBJECT_TYPE type, IntPtr instancePtr, NativeMethods.PERF_COUNTER_DEFINITION[] counters) {
            ProcessInfo processInfo = new ProcessInfo();
            for (int i = 0; i < counters.Length; i++) {
                NativeMethods.PERF_COUNTER_DEFINITION counter = counters[i];
                long value = ReadCounterValue(counter.CounterType, (IntPtr)((long)instancePtr + counter.CounterOffset));
                switch ((ValueId)counter.CounterNameTitlePtr) {
                    case ValueId.ProcessId:
                        processInfo.processId = (int)value;
                        break;
                    case ValueId.HandleCount:
                        processInfo.handleCount = (int)value;
                        break;
                    case ValueId.PoolPagedBytes:
                        processInfo.poolPagedBytes = value;
                        break;
                    case ValueId.PoolNonpagedBytes:
                        processInfo.poolNonpagedBytes = value;
                        break;
                    case ValueId.VirtualBytes:
                        processInfo.virtualBytes = value;
                        break;
                    case ValueId.VirtualBytesPeak:
                        processInfo.virtualBytesPeak = value;
                        break;
                    case ValueId.WorkingSetPeak:
                        processInfo.workingSetPeak = value;
                        break;
                    case ValueId.WorkingSet:
                        processInfo.workingSet = value;
                        break;
                    case ValueId.PageFileBytesPeak:
                        processInfo.pageFileBytesPeak = value;
                        break;
                    case ValueId.PageFileBytes:
                        processInfo.pageFileBytes = value;
                        break;
                    case ValueId.PrivateBytes:
                        processInfo.privateBytes = value;
                        break;
                    case ValueId.BasePriority:
                        processInfo.basePriority = (int)value;
                        break;
                }
            }
            return processInfo;
        }

        static ValueId GetValueId(string counterName) {
            if (counterName != null) {
                object id = valueIds[counterName];
                if (id != null)
                    return(ValueId)id;
            }
            return ValueId.Unknown;
        }

        static long ReadCounterValue(int counterType, IntPtr dataPtr) {
            if ((counterType & NativeMethods.NtPerfCounterSizeLarge) != 0)
                return Marshal.ReadInt64(dataPtr);
            else
                return(long)Marshal.ReadInt32(dataPtr);
        }

        enum ValueId {
            Unknown = -1,
            HandleCount,
            PoolPagedBytes,
            PoolNonpagedBytes,
            ElapsedTime,
            VirtualBytesPeak,
            VirtualBytes,
            PrivateBytes,
            PageFileBytes,
            PageFileBytesPeak,
            WorkingSetPeak,
            WorkingSet,
            ThreadId,
            ProcessId,
            BasePriority,
            CurrentPriority,
            UserTime,
            PrivilegedTime,
            StartAddress,
            ThreadState,
            ThreadWaitReason
        }
    }

    internal static class NtProcessInfoHelper {
        private static int GetNewBufferSize(int existingBufferSize, int requiredSize) {
            if( requiredSize == 0) {
                //
                // On some old OS like win2000, requiredSize will not be set if the buffer
                // passed to NtQuerySystemInformation is not enough.
                //
                int newSize = existingBufferSize * 2;
                if ( newSize < existingBufferSize ) { 
                    // In reality, we should never overflow.
                    // Adding the code here just in case it happens.    
                    throw new OutOfMemoryException();   
                }
                return newSize;
            }               
            else {  
                // allocating a few more kilo bytes just in case there are some new process
                // kicked in since new call to NtQuerySystemInformation
                int newSize = requiredSize + 1024 * 10;
                if ( newSize < requiredSize ) {
                    throw new OutOfMemoryException();
                }
                return newSize;
            }   
        }
        
        #pragma warning disable 169        
        public static ProcessInfo[] GetProcessInfos(Predicate<int> processIdFilter = null) {

            int requiredSize = 0;
            int status; 

            ProcessInfo[] processInfos;
            GCHandle bufferHandle = new GCHandle();

            // Start with the default buffer size.
            int bufferSize = DefaultCachedBufferSize;

            // Get the cached buffer.
            long[] buffer = Interlocked.Exchange(ref CachedBuffer, null);

            try {
                // Retry until we get all the data
                do {
                    if (buffer == null)
                    {
                        // Allocate buffer of longs since some platforms require the buffer to be 64-bit aligned.
                        buffer = new long[(bufferSize + 7) / 8];
                    }
                    else
                    {
                        // If we have cached buffer, set the size properly.
                        bufferSize = buffer.Length * sizeof(long);
                    }
                    bufferHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned);

                    status = NativeMethods.NtQuerySystemInformation(
                        NativeMethods.NtQuerySystemProcessInformation,
                        bufferHandle.AddrOfPinnedObject(),
                        bufferSize,
                        out requiredSize);

                    if ((uint)status == NativeMethods.STATUS_INFO_LENGTH_MISMATCH)
                    {
                        if (bufferHandle.IsAllocated) bufferHandle.Free();
                        buffer = null;
                        bufferSize = GetNewBufferSize(bufferSize, requiredSize);
                    }
                } while ((uint)status == NativeMethods.STATUS_INFO_LENGTH_MISMATCH);

                if (status < 0) { // see definition of NT_SUCCESS(Status) in SDK
                    throw new InvalidOperationException(SR.GetString(SR.CouldntGetProcessInfos), new Win32Exception(status));
                }

                // Parse the data block to get process information
                processInfos = GetProcessInfos(bufferHandle.AddrOfPinnedObject(), processIdFilter);
            }
            finally {
                // Cache the final buffer for use on the next call.
                Interlocked.Exchange(ref CachedBuffer, buffer);

                if (bufferHandle.IsAllocated) bufferHandle.Free();
            }

            return processInfos;
        }

        // Use a smaller buffer size on debug to ensure we hit the retry path.
#if DEBUG
        private const int DefaultCachedBufferSize = 1024;
#else
        private const int DefaultCachedBufferSize = 128 * 1024;
#endif

        // Cache a single buffer for use in GetProcessInfos().
        private static long[] CachedBuffer;

       static ProcessInfo[] GetProcessInfos(IntPtr dataPtr, Predicate<int> processIdFilter) {
            // 60 is a reasonable number for processes on a normal machine.
            Hashtable processInfos = new Hashtable(60);

            long totalOffset = 0;
            
            while(true) {
                IntPtr currentPtr = (IntPtr)((long)dataPtr + totalOffset);
                SystemProcessInformation pi = new SystemProcessInformation();

                Marshal.PtrToStructure(currentPtr, pi);

                // Process ID shouldn't overflow. OS API GetCurrentProcessID returns DWORD.
                int processInfoProcessId = pi.UniqueProcessId.ToInt32();

                if (processIdFilter == null || processIdFilter(processInfoProcessId)) {
                    // get information for a process
                    ProcessInfo processInfo = new ProcessInfo();
                    processInfo.processId = processInfoProcessId;
                    processInfo.handleCount = (int)pi.HandleCount;
                    processInfo.sessionId = (int)pi.SessionId;                
                    processInfo.poolPagedBytes = (long)pi.QuotaPagedPoolUsage;;
                    processInfo.poolNonpagedBytes = (long)pi.QuotaNonPagedPoolUsage;
                    processInfo.virtualBytes = (long)pi.VirtualSize;
                    processInfo.virtualBytesPeak = (long)pi.PeakVirtualSize;
                    processInfo.workingSetPeak = (long)pi.PeakWorkingSetSize;
                    processInfo.workingSet = (long)pi.WorkingSetSize;
                    processInfo.pageFileBytesPeak = (long)pi.PeakPagefileUsage;
                    processInfo.pageFileBytes = (long)pi.PagefileUsage;
                    processInfo.privateBytes = (long)pi.PrivatePageCount;
                    processInfo.basePriority = pi.BasePriority;


                    if( pi.NamePtr == IntPtr.Zero) {                    
                        if( processInfo.processId == NtProcessManager.SystemProcessID) {
                            processInfo.processName = "System";
                        }
                        else if( processInfo.processId == NtProcessManager.IdleProcessID) {
                            processInfo.processName = "Idle";
                        }
                        else { 
                            // for normal process without name, using the process ID. 
                            processInfo.processName = processInfo.processId.ToString(CultureInfo.InvariantCulture);
                        }
                    }
                    else {                     
                        string processName = GetProcessShortName(Marshal.PtrToStringUni(pi.NamePtr, pi.NameLength/sizeof(char)));  
                        //
                        // On old operating system (NT4 and windows 2000), the process name might be truncated to 15 
                        // characters. For example, aspnet_admin.exe will show up in performance counter as aspnet_admin.ex.
                        // Process class try to return a nicer name. We used to get the main module name for a process and 
                        // use that as the process name. However normal user doesn't have access to module information, 
                        // so normal user will see an exception when we try to get a truncated process name.
                        //                    
                        if (ProcessManager.IsOSOlderThanXP && (processName.Length == 15)) {
                            if (processName.EndsWith(".", StringComparison.OrdinalIgnoreCase)) {
                                processName = processName.Substring(0, 14);
                            }
                            else if (processName.EndsWith(".e", StringComparison.OrdinalIgnoreCase)) {
                                processName = processName.Substring(0, 13);
                            }
                            else if (processName.EndsWith(".ex", StringComparison.OrdinalIgnoreCase)) {
                                processName = processName.Substring(0, 12);
                            }
                        }
                        processInfo.processName = processName;                                          
                    }

                    // get the threads for current process
                    processInfos[processInfo.processId] =  processInfo;

                    currentPtr = (IntPtr)((long)currentPtr + Marshal.SizeOf(pi));
                    int i = 0;
                    while( i < pi.NumberOfThreads) {
                        SystemThreadInformation ti = new SystemThreadInformation();
                        Marshal.PtrToStructure(currentPtr, ti);                    
                        ThreadInfo threadInfo = new ThreadInfo();                    

                        threadInfo.processId = (int)ti.UniqueProcess;
                        threadInfo.threadId = (int)ti.UniqueThread;
                        threadInfo.basePriority = ti.BasePriority;
                        threadInfo.currentPriority = ti.Priority;
                        threadInfo.startAddress = ti.StartAddress;
                        threadInfo.threadState = (ThreadState)ti.ThreadState;
                        threadInfo.threadWaitReason = NtProcessManager.GetThreadWaitReason((int)ti.WaitReason);

                        processInfo.threadInfoList.Add(threadInfo);
                        currentPtr = (IntPtr)((long)currentPtr + Marshal.SizeOf(ti));
                        i++;
                    }
                }

                if (pi.NextEntryOffset == 0) {
                    break;
                }
                totalOffset += pi.NextEntryOffset;
            }

            ProcessInfo[] temp = new ProcessInfo[processInfos.Values.Count];
            processInfos.Values.CopyTo(temp, 0);
            return temp;
        }

        // This function generates the short form of process name. 
        //
        // This is from GetProcessShortName in NT code base. 
        // Check base\screg\winreg\perfdlls\process\perfsprc.c for details.
        internal static string GetProcessShortName(String name)  {         
            if (String.IsNullOrEmpty(name)) {
                Debug.WriteLineIf(Process.processTracing.TraceVerbose, "GetProcessInfos() - unexpected blank ProcessName");
                return String.Empty;
            }

            int slash   = -1;
            int period  = -1;

            for (int i = 0; i < name.Length; i++) {
                if (name[i] == '\\')
                    slash = i;
                else if (name[i] == '.')
                    period = i;                
            }

            if (period == -1)
                period = name.Length - 1; // set to end of string
            else {
                // if a period was found, then see if the extension is
                // .EXE, if so drop it, if not, then use end of string
                // (i.e. include extension in name)
                String extension = name.Substring(period);

                if(String.Equals(".exe", extension, StringComparison.OrdinalIgnoreCase) )
                    period--;                 // point to character before period
                else
                    period = name.Length - 1; // set to end of string
            }

            if (slash == -1) 
                slash = 0;     // set to start of string
            else
                slash++;       // point to character next to slash

            // copy characters between period (or end of string) and
            // slash (or start of string) to make image name
            return name.Substring(slash, period - slash + 1);
        }

        // native struct defined in ntexapi.h
        [StructLayout(LayoutKind.Sequential)]
        internal class SystemProcessInformation {
            internal uint NextEntryOffset;
            internal uint NumberOfThreads;
            long SpareLi1;
            long SpareLi2;
            long SpareLi3;
            long CreateTime;
            long UserTime;
            long KernelTime;

            internal ushort NameLength;   // UNICODE_STRING   
            internal ushort MaximumNameLength;
            internal IntPtr NamePtr;     // This will point into the data block returned by NtQuerySystemInformation

            internal int BasePriority;
            internal IntPtr UniqueProcessId;
            internal IntPtr InheritedFromUniqueProcessId;
            internal uint HandleCount;
            internal uint SessionId;
            internal UIntPtr PageDirectoryBase;
            internal UIntPtr PeakVirtualSize;  // SIZE_T
            internal UIntPtr VirtualSize;
            internal uint   PageFaultCount;

            internal UIntPtr PeakWorkingSetSize;
            internal UIntPtr WorkingSetSize;
            internal UIntPtr QuotaPeakPagedPoolUsage;
            internal UIntPtr QuotaPagedPoolUsage;
            internal UIntPtr QuotaPeakNonPagedPoolUsage;
            internal UIntPtr QuotaNonPagedPoolUsage;
            internal UIntPtr PagefileUsage;
            internal UIntPtr PeakPagefileUsage;
            internal UIntPtr PrivatePageCount;

            long ReadOperationCount;
            long WriteOperationCount;
            long OtherOperationCount;
            long ReadTransferCount;
            long WriteTransferCount;
            long OtherTransferCount;
        }

        [StructLayout(LayoutKind.Sequential)]
        internal class SystemThreadInformation {
            long KernelTime;
            long UserTime;
            long CreateTime;

            uint WaitTime;
            internal IntPtr StartAddress;
            internal IntPtr UniqueProcess;
            internal IntPtr UniqueThread;
            internal int Priority;
            internal int BasePriority;
            internal uint ContextSwitches;
            internal uint ThreadState;
            internal uint WaitReason;
        }         
        #pragma warning restore 169        
    }
}
#endif // !FEATURE_PAL
